Cut 1 to 2 tablespoons unsalted butter into 4 pieces and place on the edge of a cutting board or in a small bowl and let come to room temperature while you prepare the corn.
Heat an air fryer to 400ºF. Meanwhile, shuck 4 ears corn if needed. If needed, cut each corn in half to fit in the air fryer in a single layer.
Rub then corn all over with 1 teaspoon olive oil and sprinkle with 1/4 teaspoon kosher salt. Working in batches if needed, place in the air fryer basket in a single layer, making sure they do not overlap.
Air fry until tender and lightly charred around the edges, flipping halfway through, 6 to 8 minutes total.Rub all over with the butter. Sprinkle with more kosher salt if desired.